<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let str = 'hello word';
        let re = str.startsWith('he'); //以啥开头 返回ture
        let rw = str.endsWith('ord'); //以啥结尾
        console.log(re);
        console.log(rw);

        console.log("y".repeat(5)); //重复字符串n次
        console.log(str.repeat(2));
    </script>
</body>

</html>